I have a M1 Pro from work and it surely won't last that while working. Throw some video calls at it and working outside (so, screen at the brightest level) and at the end of the work day I have to plug it in

With load on it and a bright room (= display reasonably bright as well) my M3 also doesn't always last 8h. But it gets very close. Intel machines are more like 3h in that case.

Your M1 Pro is 5 years old presumably?